If you haven’t filed your 2011 tax return and claimed your refund yet, you may be one of the 1.2 million taxpayers that are owed $1 billion in 2011 tax refunds. The IRS estimates more than half of the refunds are for at least $698.

When is the deadline to claim your 2011 tax refund?The clock is ticking, so you’d better act fast if you want your tax refund. You need to file a return for 2011 no later than April 15th, 2015. If you don’t file by then, the monies will be handed over to the US Treasury.

The total tax refunds may be even higherIf you don’t file a tax return, the IRS does it for you in what is called a substitute for a return or ghost return. The return is constructed based on the income reported by third parties on W-2 and 1099 forms. However, the IRS usually claims the standard deduction for you as they don’t have access to your itemized deductions and the associated supporting documentation. Therefore, there could potentially be than the $1 billion in reported unclaimed tax refunds as itemized deductions haven’t been applied to these ghost returns.

Why is there so much in unclaimed tax refunds?In some cases, people earned too little income so they didn’t need to file a tax return, even though they had taxes withheld from their wages, or they made quarterly estimated tax payments.

In other cases, people with low or moderate incomes might not have claimed the maximum Earned Income Tax Credit (EITC) of $5,751 for having three or more children. You might have been eligible for the EITC in 2011 if you had three or more children and earned less than $43,998 ($49,078 married filing jointly). The income limit was $40,964 ($46,044 married filing jointly) for those with two children. The income limit was $36,052 ($41,132 married filing jointly) for those with one child, and $13,660 ($18,740 married filing jointly) for those who were childless.

Do I simply need to file a 2011 tax return to get the money owed to me?While you just need to submit your return to claim a refund, the money won’t be sent to you unless your financial house is in order. You must have filed your tax returns for 2012 and 2013. And if you owe money to the IRS, your refund will be applied to that balance. It also might be used to offset unpaid child support or federal debts, like student loans.